With the advent of sophisticated equipment in the electrical and electronic fields, it has become necessary that the components of the various pieces of equipment conform to high standards which are set forth in the specifications for these components. For example, circuit boards which are used in relatively complicated pieces of equipment, such as main frame computers, must be of a relatively high standard of quality in order to function in an efficient manner for a long period of time without deteriorating or breaking down, and thus causing an interruption in the function of the machine. This high quality of material is opposed to pieces of equipment requiring a lower standard of quality such as those used in personal computers, high quality television equipment, radios, etc.
Circuit boards upon which a circuit is etched or implanted usually comprise a laminate which is composed of a synthetic polymeric substance which possesses desirable characteristics such as thermal stability, low coefficient of thermal expansion, dimensional stability, low dielectric constant, solvent resistance, low moisture absorption, etc., and a suitable reinforcement matrix, such as glass, quartz, graphite, Kevlar, etc.
As will hereinafter be shown, it has now been discovered of that certain thermoset polymers of polyvinyl benzyl ethers) of polyphenols may be utilized as a component in the preparation of laminates which themselves will form a component of a circuit board and will possess the desirable characteristics hereinbefore set forth. The aforesaid thermoset polymers are derived or prepared from materials which comprise poly(vinyl benzyl ethers) of polyphenols having certain configuration. Alternatively, these compounds may also be designated as styrene terminated tetrakis phenols. The compounds which are used to form the polymers of the present invention differ from those which are described in U.S. Pat. No. 4,116,936 in that the compounds of the patent are bifunctional in nature in contrast to the compounds of the present invention which may be designated as multi- or polyfunctional in nature and which possess four or more functionalities.
By utilizing polymers which are obtained from the compounds of the present invention, it is possible for the users to avail themselves of certain advantages which are inherent between these compounds and the compounds described in U.S. Pat. No. 4,116,936. For example, the styrenated materials formed from the polyphenols of the present invention are non-crystalline in nature and possess a better solubility in resin formulations in both the A and B stage. Therefore, the polymers will stay in solution in the resultant formulation and crystallize out on standing. In addition, the polymers of the present invention will form excellent films during the B stage processing of the resin formulation and will be less likely to be brittle or flake off of the reinforcement upon which the formulation is impregnated.